The objectives of this project are to fully characterize and to study the activities of pertussigen, a substance from Bordetella pertussis, and to find the role that this and other substances play in the action of B. pertussis. Methods to obtain pertussigen in highly purified form have been developed, and with these preparations we are studying their ability to protect mice from experimental pertussis. The effect that other substances from B. pertussis have on the protective effect of pertussigen is presently under investigation. Particular attention has been given to the mechanisms by which studies indicate that pertussigen may act directly on the lymphoid cells responsible for antibody production.